This invention relates generally to an improved dispensing means for discharging a viscous material, and more particularly to such dispensing means having a feature which permits dispensing of viscous material both through a nozzle and through a sac nozzle inserted through such nozzle, as well as a feature which facilitates dispensing of highly viscous material through such nozzle and such sac nozzle inserted through such nozzle, controls the quantity of viscous material ejected through such nozzle and such sac nozzle inserted through such nozzle, reduces dripping of less viscous, watery material through such nozzle and such sac nozzle inserted through such nozzle, and minimizes the possibility of introducing contaminants from the outside through such nozzle and such sac nozzle inserted through such nozzle.
Product dispensers generally of the type described herein, as including a reservoir having a basal dispensing opening; manual urging means actuatable to pressurize viscous material in said basal dispensing opening; and a vent for venting said reservoir prior to actuation of said manual urging means are known as having means provided for dispensing viscous material contained in a sac contained inside said reservoir, through a nozzle in said basal dispensing opening.
For example, dispensing devices having means provided for dispensing viscous material contained in a sac inside a reservoir through a resilient, tubular nozzle in the bottom wall of the sac are well known. A manual plunger may be actuated to exert mechanical pressure on a portion of said resilient, tubular nozzle, thus dispensing viscous material contained in said nozzle portion.
While these nozzles have generally performed satisfactorily, they are not without their shortcomings. For example, the resilient, tubular nozzle must be affixed to the sac in a substantially leak-proof manner. Since the sac and nozzle are generally made of different materials, additional time and material is expended to achieve these intended functions. Moreover, upon releasing the manual plunger, viscous material contained in the sac is urged to flow into the nozzle portion solely by the force of gravity and the minor pressure differential created in the resilient nozzle portion as the nozzle portion rebounds from a flattened to an tubular shape. For highly viscous material, these forces may be insufficient to fill the nozzle portion before subsequent actuation of the manual plunger, thus reducing the quantity of viscous material dispensed through the nozzle. Furthermore, no means are provided to prevent leakage of less viscous, watery materials through the nozzle when the manual plunger is unactuated. Additionally, the manual plunger exerts even mechanical pressure along the resilient tubular nozzle portion when the plunger is actuated so that the pressure differential between the pressure of viscous material at the entrance of the nozzle portion and the ambient air pressure at the exit of the nozzle portion urges the viscous material to dispense through the exit of the nozzle portion. However, when the pressure of viscous material at the entrance of the nozzle portion resulting from the force of gravity acting on the viscous material is reduced as the viscous material remaining in the sac is depleted, or when the material at the exit of the nozzle portion is more viscous as a result of drying, the pressure differential between the pressure of viscous material at the entrance of the nozzle portion and the ambient air pressure at the exit of the nozzle portion may urge the viscous material to re-enter the sac through the entrance of the nozzle portion when the manual plunger is actuated, and the resultant backflow may reduce, if not eliminate, the quantity of viscous material dispensed through the nozzle.
Other product dispensers generally of the type described herein, as including a reservoir having a basal dispensing opening; an air chamber; manual pumping means actuatable to pressurize air in said air chamber; venting means for venting said air chamber prior to actuation of said pumping means; means for communicating pressurized air from said air chamber to said reservoir; and means for selectively blocking the dispensing of material are known as having means provided for dispensing viscous material contained in said reservoir through a nozzle in said basal dispensing opening, or for dispensing viscous material contained in a sac in said reservoir, through a sac nozzle in said basal dispensing opening.
U.S. Pat. No. 5,115,945 discloses a dispensing device having means provided for dispensing viscous material contained in a reservoir through a resilient, tubular nozzle which is held in place in a basal dispensing opening by internal and external snap rings. Such means also provides for dispensing viscous material contained in a sac inside the reservoir through a resilient, tubular nozzle in the bottom wall of the sac which is held in place in the basal dispensing opening by internal and external snap rings. Thus, the dispensing device permits removal of the original nozzle from the basal dispensing opening and insertion of a sac incorporating a similar nozzle in the bottom wall of the sac into the reservoir, with the sac nozzle replacing the original nozzle in the basal dispensing opening.
While these nozzles have generally performed satisfactorily, they are not without their shortcomings. For example, the resilient, tubular nozzle must be affixed to the sac in a substantially leak-proof manner. Since the sac and nozzle are generally made of different materials, additional time and material is expended to achieve these intended functions. Moreover, insertion and removal of the original resilient, tubular nozzle is time-consuming and the original nozzle may get lost between uses. Furthermore, if the original nozzle or the nozzle on the sac is not properly pulled through the basal dispensing opening, or if there is a residue of reservoir material remaining around the basal dispensing opening accepting the nozzle snap rings, the seal between the nozzle and the reservoir bottom wall may not be air-tight or leak-proof, reducing the efficiency of pressurizing the reservoir and making the dispensing of viscous material difficult if not impossible. In addition, highly viscous material often requires several pumps to build sufficient pressure in the reservoir to dispense the desired quantity of product through the nozzle. Moreover, the quantity of material dispensed per pumping action varies because it is a function of the pressure in the reservoir and the length of time the manual pump is held depressed. Furthermore, the nozzle remains open for as long as the manual pump is held depressed. Thus, when dispensing less viscous, watery product, dripping from the nozzle may result. Additionally, when the manual pump is held depressed, the passageway from the reservoir through the nozzle to the exterior remains open, rendering the reservoir contents susceptible to contamination introduced from the exterior through the open nozzle into the reservoir.